Interestingly, Loramus appears in Legion as the Razelikh-possessed version of himself, and joins the Illidari on the Fel Hammer, a structure in the Demon Hunter starting zone. The Fel Hammer eventually becomes the Demon Hunter Order Hall.Razelikh sometimes takes control and threatens the Illidari, but Loramus stays in prison to keep Razelikh from attacking the others (Source).

Patto di Sangue dell'Ingannatore (Sciamano) - "Ner'zhul, Elder Shaman of the Shadowmoon Clan, wanted to save his people and finally obtain the power and respect he so dearly desired. But he was deceived..."

Pilastri del Portale Oscuro (Stregone) - "Corrupted by the demonlord Sargeras, Medivh contacted the orc warlock Gul'dan and together they opened the Dark Portal, allowing the Burning Legion to begin its invasion of Azeroth."

Perfidia dei Sin'dorei (Stregone) - "So many of our people have been twisted and dominated by the Burning Legion. It's only fitting that we in turn use their own armies against them."

UPDATE: The latest Beta patch has adjusted many of the passive effects of these legendaries. The following represents the most current in-game data as of August 26/16 (many of the Wowhead tooltips have not been updated yet!)

This is one of the new legendary world drops that are coming in Legion. Some of these drops are class-specific, and others are shared between classes (or have no class requirement at all!)

At the beginning of Legion, only 1 legendary item can be equipped at a time. Over time, as the expansion progresses this cap will be increased (Source).

Here is some further information about these items:

The legendary items are intended to be used for the entire expansion. They are currently item level 895, and it remains to be seen whether this will change prior to release, or during Legion itself (for comparison, Mythic mode gear from Incubo di Smeraldo is iLvl 880).

Thus far, it appears that legendaries will drop from dungeon bosses, raid bosses, PvP Strongboxes, Mythic+ Weekly Caches and World Quest Caches (rewarded after completing 4 world quests). As it stands, these will be the ONLY sources that will yield legendaries. Blizzard may expand where they can come from in the future (Source: Legion Summit Dev Interview, Video | Text Summary; June 16 Legion Live Developer Q & A, 53:30)

While the legendaries are rare drops, they are not fully random - there will be ways to target specific items (Source).

More difficult content will have a higher chance of dropping these items (Source)

It should be nearly impossible to get a duplicate legendary item. (Source: Legion Summit Dev Interview, Video | Text Summary)

Some level of bad luck streak protection also applies to legendary items (i.e. the chances of you getting a legendary will slowly increase if you don't have one drop). (Source: Legion Summit Dev Interview, Video | Text Summary)

If the slot for the item is transmoggable, you can transmog these legendaries to other appearances, and vice versa (unlike legendary items from previous expansions) (Source)

Legion legendary procs/effects will be disabled in instanced PvP (Source)

Blizzard plans to institute a "suppression aura" in effect for a certain number of weeks after Mythic raids are available, which would disable any legendary item passive effects (they would still function normally as high-ilvl regular items, with the primary/secondary stats intact). (Source)

UPDATE - As per the latest information, Legion legendaries WILL BE allowed in all raid situations, INCLUDING Mythic difficulty. The previously noted "suppression aura" in Mythic will not be implemented. (Source: Legion Summit Dev Interview, Video | Text Summary)

All legendary bonus effects are passive "Equip" effects (there are no "Use" effects on these items)All Legion legendaries are Bind-on-Pickup, and cannot be sold, traded or listed on the Auction House.